expiratory valves.

Expiratory Unidirectional valve

Expiratory valve - Normal

Incompetent expiratory valve

The capnogram shows prolonged phase II as well as slanting of descending limb of inspiratory segement. The expiratory unidirectional valve was noted to be fixed in the open position and thus allowing previously exhaled gases, high in CO2, to be rebreathed with each inspiration. The CO2 waveform returned to normal soon after the valve was removed, cleaned, dried, and replaced.